Powertrain including input disconnect and accessory drive system for an electrically variable transmission

Abstract

A vehicle powertrain includes an engine connected to an input torque device including a torque isolator. A plurality of intermeshed accessory drive gears are connected to the torque device for driving accessories. A hybrid electromechanical transmission is connected to one of the accessory drive gears. A motor / generator of the hybrid electromechanical transmission is operable to drive the accessory drive gears when the engine is not running.

Description

TECHNICAL FIELD[0001]The present invention relates to an input disconnect and accessory drive system for an electrically variable transmission in a powertrain wherein accessory drive gears are connected between an electrically variable transmission and an engine such that accessories may be driven by an electric motor in the transmission when the engine is not running.BACKGROUND OF THE INVENTION[0002]The purpose of a vehicular transmission is to provide a neutral, at least one reverse and one or more forward driving ranges that impart power from an engine, and / or other power sources, to the drive members which deliver the tractive effort from the vehicle to the terrain over which the vehicle is being driven. As such, the drive members may be front wheels, rear wheels or a track, as required to provide the desired performance.[0003]A series propulsion system is a system in which energy follows a path from an engine to an electric storage device and then to an electrical motor which a...

AI Technical Summary

Benefits of technology

[0019]The invention provides a vehicle powertrain with an electrically variable transmission connected to an engine via accessory drive gears. Accordingly, a motor / generator of the electrically variable transmission may be used to drive the accessories via the accessory drive gears when the engine is not running. An input torque transfer device and torque isolator may also be provided on the engine to disconnect the engine from the transmission and to provide damping of driveline excitation so that the accessories and transmission do not receive excitation from engine vibrations.

Problems solved by technology

However, such combinations of small APUs and even large energy storage devices do not accommodate high-average power vehicles or address duty cycles that demand continuous, constant speed operation.

Steep grades and sustained high-average cruising speeds at desired high efficiencies are not achievable with a typical, series, hybrid transmission configuration.

The challenge, therefore, is to provide a power system that will operate at high efficiencies over a wide variety of operating conditions.

However, when the two gear members rotate in the same direction, but at different speeds, the direction in which the third gear member rotates may often be determined simply by visual analysis, but in many situations the direction will not be obvious and can only be determined by knowing the number of teeth present in the gear members of the planetary gear set.

The lack of a mechanical point is a drawback inasmuch as the maximum mechanical efficiency in the transfer of power from the engine to the output occurs when one of the motor / generators is at a mechanical point, i.e., stationary.

In addition to the accessory motor, a controller and high voltage wiring are also required, which add further cost and weight.

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